VISUAL LOCALIZATION OF UNMANNED AERIAL VEHICLES BASED ON MARKER DETECTION AND PROCESSING

A method for locating markers in an image captured by a mobile device moving about an operating space. The method includes preprocessing an image to generate a set of image data, locating fixed features of markers by tracing edges of the fixed features, and extracting variable data payloads of each of the markers associated with the located fixed features. The fixed features of each of the markers may include a pair of parallel lines extending along opposite sides of a data area containing the variable data payload, and each of the lines extends a distance beyond each exposed end of the data area to avoid missing data when markers are not arranged orthogonally to the scan direction. The preprocessing involves rotating or skewing the image to provide rotated or skewed versions of the image to facilitate locating markers regardless of their angular orientation in the image.